/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace NMS
{
	/// <summary>
	/// A delegate that can receive messages async.
	/// </summary>
	public delegate void MessageListener(IMessage message);

	/// <summary>
	/// A consumer of messages
	/// </summary>
	public interface IMessageConsumer : System.IDisposable
    {
        
        /// <summary>
        /// Waits until a message is available and returns it
        /// </summary>
        IMessage Receive();
        
        /// <summary>
        /// If a message is available within the timeout duration it is returned otherwise this method returns null
        /// </summary>
        IMessage Receive(System.TimeSpan timeout);
        
        /// <summary>
        /// If a message is available immediately it is returned otherwise this method returns null
        /// </summary>
        IMessage ReceiveNoWait();
        
        /// <summary>
        /// An asynchronous listener which can be used to consume messages asynchronously
        /// </summary>
        event MessageListener Listener;

        /// <summary>
        /// Closes the message consumer. 
        /// </summary>
        /// <remarks>
        /// Clients should close message consumers them when they are not needed.
        /// This call blocks until a receive or message listener in progress has completed.
        /// A blocked message consumer receive call returns null when this message consumer is closed.
        /// </remarks>
        void Close();
    }
}


